Lung cancer is the leading cause of cancer-related mortality in the United States, with 159 000 deaths estimated in 2014. Age older than 55 years and smoking are the strongest risk factors for lung cancer. Smoking cessation is the main intervention to prevent lung cancer in the 20% of Americans who continue to smoke, but only 15% of cessation efforts succeed. Outcomes in lung cancer depend crucially on the stage of diagnosis, with 5-year survival for non–small cell lung cancer estimated at 71% to 90% for stage IA and 42% to 75% for stage IB cases, compared with less than 10% for those diagnosed with stage IV.1 Currently only 15% of lung cancer cases are diagnosed at stage I, and large trials have not supported the value of chest radiography or sputum cytology for screening.2 Low-dose computed tomography (CT) has emerged as a potentially useful screening method, with 55% to 85% of detected cancers found to be stage I.3,4 Approximately 9 million Americans would potentially be eligible for this screening guideline, divided roughly equally between current smokers and former smokers who have quit within the past 15 years.